Piston lubricator and cylinder dust guard



De@ 4, 1956 E. w. PATTERSON 2,772,751

PISTON LUBRICATOR AND CYLINDER DUST GUARD Filed Sept. 29, 1954 i @6F19 (a AWEQSO/J, 5 IN V EN TOR.

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United States Patent l PISTON LUBRICATOR AND CYLINDER DUST GUARD Edgar W. Patterson, Downey, Calif. Application September 29, 1954, Serial No. 459,025

4 Claims. (Cl. 184-18) This invention relates to air cylinders used for counter balancing a string of sucker rods in a sucker rod reciprocator employed in the producing of oil from a deep well. 1t particularly relates to such an air cylinder as is equipped with a piston having such a substantial length/diameter ratio and tting said cylinder with suliicient closeness to be self-guided in approximate co-axial alignment with said cylinder.

There are three major problems met with in the operation of such air cylinders. The tirst of these problems is the provision of adequate lubrication between the piston and the cylinder. The second problem is to recover oil which escapes downwardly between the piston and the cylinder from the high pressure side of the latter to the low pressure side thereof. The third problem requiring solution in the operation of this type of air cylinder is the tendency of dust to collect on the inner face of the cylinder wall where this travels downwardly past the piston, as this dust tends to be drawn upwardly between the piston and the cylinder on the return movement of the latter where it operates as an abrasive causing excessive wear of the cylinder and the piston.

The recapture of oil escaping downwardly past the piston has been accomplished in various ways. In my prior Patent No. 2,665,901 an oil reservoir is provided in the lower end of the cylinder in which oil escaping downwardly past the piston collects and from which this oil is reconveyed to the pressure chamber of the cylin- Ader by a pump located in said reservoir and operated by contact with the piston. In spite of the good features of that particular arrangement, the large volume of air which necessarily must be displaced from the open end of the cylinder during each stroke, causes the introduction of dust into the oil reservoir which is sucked in with said air as the cylinder moves downward.

Another solution of the problem `of 'recovering oil carried downwardly past the piston `is disclosed iu my Patent No. 2,665,774, which embodies an oil reservoir within the lower end of the piston and a scraping means for scraping` excess oil from the cylinder wall as the cylinder travels downwardly, this oil being delivered into said reservoir. A pump means, operated by vthe reciprocation of the cylinder, returns the voil so captured to the pressure chamber of the cylinder. v

The latter invention has the advantage of removing all the oil from the cylinder wall but a very thin iilm. This practically eliminates the escape of oil by a downward flow ofv oil from the lower end of the cylinder. It also minimizesv the amount of dust deposited on the cylinder wall by air sucked into the lowerend of the cylinder with each downward movementl of the latter. This result proceeds partly from the fact that the lower end of the cylinder is wide open, thus allowing movement of air into and from the cylinder at-a relatively low speed. Then the extremely small amount of oil adhering to the` cylinder wall is relatively unattractive to the dust. y

In spite of the excellent characteristics .of the device M3ice covered by Patent No. 2,665,774 in minimizing the amount of dust admitted thereto from the atmosphere, it is an object of thepresent invention to still further decrease the abrasive action caused by dust gaining access to the wearing surfaces of the piston and cylinder.

The general mode of operation of the present invention is to greatly reduce the amount of air allowed to have access to the inner face of the cylinder during each downward and upward reciprocation of the latter. This is done by the mounting of a dust guard apron on a self-guided piston which is held in concentricity with the cylinder by the piston so that it does not touch the cylinder, this sleeve, however, being of such a diameter that it lies in very closely spaced relation with the inner surface of the cylinder.

By virtue of therprovision of oil scraping means in the combination to which this invention relates, oil is not allowed to flow downwardly from between the piston and cylinder and thus the cylinder wall remains covered only with too thin a film of oil for this to ow by gravity. Furthermore, no oil at all is allowed to flow downwardly over the dust guard apron. Thus a minimum amount of atmospheric dust is allowed to have access to the thin film of oil on the cylinder wall and no opportunity is given for dust to collect on the dust guard apron because the latter is completely free of oil.

' While a means for scraping the oil from the cylinder wall as the latter moves downwardly past the piston is essential to the present invention, the latter is not limited to the particular such means shown in my U. S. Letters Patent No. 2,665,774.

It is, in fact, another object of the present invention to provide a piston lubricator and cylinder dust guard functioning in accordance with the mode of operation above pointed out which may utilize a relatively conventional self-aligning piston While still including oil recovery means for collecting said oil and returning the same into the pressure chamber of the cylinder.

The manner of accomplishing `the foregoing objects as well as further objects and advantages will be made manifest in the following description taken in connection with the accompanying drawings in which Fig, 1 isk a vertical sectional view of a preferred embodiment of the invention associated with a special type of piston shown in my Patent No. 2,665,774.

Fig. 2 is a similar view of the invention embodied with a conventional type of piston modified to provide oil scraping rings in the lower ring grooves, with the dust guard constituting a reservoir for the oil thus recovered, and with a stationary pump actuated by the reciprocating cylinder, to pump this oil back to the piston.

Fig. 3 is an enlarged detail sectional view of one of the oil scraping rings shown in both of Figsl and 2.

Referring specifically to the drawings, the invention is shown in Fig. 1 as embodied with a counter-balancing air lcylinder 10 which is open at its lower end, and is closed at its upper end by a head 11 having a universal mounting 12. The cylinder 10 is suspended by this mounting from a walking beam (not shown) which is part of a reciprocator for reciprocating a string of sucker rods leading down to the plunger oi' a pump in a deep oil well. A disclosure of such a reciprocator may be found in my Patent No. 2,665,774.

Fixed on cylinder 10 and extending laterally therefrom at its lower end is a bracket 13 in which a pump actuator 14` is secured by a set screw 15 to permit vertical adjustment of `the actuator relative to the cylinder.

- Vertical oscillation of the walking beam from which the cylinder 10 is suspended causes said cylinder to reciprocate upon Ya relatively stationary piston 16 -fixed.

on the upper end of a hollow piston rod 17, the lower 3 end of which is closed by a T-head 18 which-pivots in bearings 19 provided on a xed base 20.

The piston 16 is cup-shaped to form an upper reservoir 25 and has a lower separatercup 26 formed integrally with the mounting hub 27 of thepiston. Ports 28 in the wall of piston 16 permit oil to flow outwardly and lubricate the outer face 29 of the piston'16 and the inner face 30 of the cylinder 1d. A groove 31 in the piston uniformly distributes this oil.

An overflow tube 32, cast integral with the piston 16, determines the maximum level at which oil is innintained in the reservoir 25.

The piston 16 is grooved below the oil groove 31 to mount split compression rings 33 thereon.

The cup 26 is shaped like the piston 16 although of less height and provides a secondary oil reservoir 34. It is of the same outside diameter as the piston 16 and has ring grooves 35 which are connected by ports V36 with reservoir 34 and have oil scraping split rings 37 mounted therein. A tube 38 is fixed in a hole provided in the cup 26 to equalize the air pressure between said cup and piston 16 with that of the atmosphere.

The lower end of the cup 26 is turned down and fitted with a cylindrical dust guard 42 of thin sheet metal which is secured in place by screws 43. The dust guard 42 is of an outside diameter to space this uniformly about one-eighth of an inch from the inner cylinder face 30, and of course is stationary while the cylinder reciprocates relative thereto.

Mounted on a bracket 44 provided on the T-head 18 is a single acting oil pump 45 having check-valved intake and discharge pipes 46 and 47 which lead respectively to reservoirs 34 and 25. Pump 45 has a spring biased plunger 48 aligned with and in the downward path of actuator 14 so as to be actuated to pump oil from the reservoir 34 to the piston reservoir 25 with each reciprocation of cylinder 10. p

The oil thus pumped from secondary oil reservoir 34 to piston reservoir 25 is oil that has leaked downwardly past rings 33 (as cylinder 10 travels downward) and has been scraped from the internal cylinder face 30 by the scraper rings 37 so as to flow from these through ports 36 into reservoir 34.

This piston lubricating means is disclosed in my Patent No. 2,665,774 and is here shown as associated with the novel dust guard 42. Mounted on the cup 26, this guard protects the oily surface 3G of cylinder 10'from the deposit of dust thereon by greatly reducing the volume of air allowed to have access to this surface `and eliminating the breathing action which sucks a large volume of air into the lower end ofthe cylinder with each down stroke and exhales this on the up stroke.

In the present invention, the cylinder 10 merely overrides a thin layer of air adjacent the guard 42, onits down stroke, and then moves up away from over this layer on its upstroke. It is, of course, a different layer of air during each stroke but the relatively small volume of this air greatly reduces the amount of dust which thus gains access to the inner surface 30 of the cylinder 10.

The form of the invention shown in Fig. 2 includes an air counter-balancing cylinder 50 which is constructed and mounted like cylinder 10. Cylinder 50 has an adjustable actuator 51 and reciprocates vertically on a substantially stationary piston 52 of conventional design whichiis mountedon a'hollow rod 53. The lower end of this rod is pivotally mounted on a base 54 and carries an oil pump 55 which is operated by actuator 51 to draw oil from an intake pipe 56 and discharge the same through a pipe 57.

The piston 52 has a hub 60 and outer wall 61 which combine to forma primary oil reservoir62 above said hub. A 'vertical overow tube 63, cast integral with the.,pist6n, determines the'maxi'rnum level of oil in said reservoir. This oil may ilow through ports l64'into an oil groove 65 and lubricate the -external face 66 of the piston 52 and the inner face 67 of cylinder 50. The piston 52 is grooved to carry air compression rings 68 and oil scraping rings 69, ports 70 opening inwardly .from the latter through wall 61.

A lower end portion of wall 61 is turned down to snugly receive the upper-end of a cylindrical sheet metal dust guard 75 whichis'secured in place by screws 76.

rl`he guard 75 is uniformly spaced from cylinder face 67 about one-eighth of an inch and extends down approximately' to the lowermost point of travel of the lowercnd ofcylinder 50. Here the guard 75 is shaped inwardly and upwardly to form a bottom 77 and concentric inner wall 78'whichprovide a secondary oil reservoir 79. The Wall 73 closely tits the piston rod 53 and is internally grooved to receive an O-ring Si! which forms a seal between the piston rod and wall '78.

Apressureequalizing tube 85 is mounted in and extends up through bottom 77 to a point above wall 7S to maintainatmo'spheric pressure-within guard 75. The tube'SS ispreferablypacked with a loose air ltering material such as'felt.

Intake pipe 56 connects with bottom 77 to conduct oil from r`eservoir'79V to pump 55.

Discharge pipe 57 extends up through guard bottom 77 and Vpiston hub 60 to discharge oil from pump 55 into piston reservoir 62.

ln the'mo'di'fed form of the invention shown in Fig. 2, just described, the dust guard 75 gives the same dust protection as the guard 42 in'the preferred embodiment and also provides in its lower end a secondary oil reservoir for collecting the oil scraped from the cylinder wall.

It will be seen that the modified form of the invention shown in'Fig. 2 may be produced by a few simple operations on the air balance cylinder shown in my Patent No. 2,665,901. This conversion is relatively inexpensive a'nd has the great merit of not only providing greatly increased protection of the lubricating oil from dust vbut also effects the return of the recovered oil by a relatively stationary pump instead of a pump which is mounted on the cylinder and reciprocates therewith as shown in said patent.

As air balance cylinders 'are in general use in many thousand 'sucker rod reciprocators throughout the petroleum industryl and as amajor portion of these have lubricating systems as'shown in Fig. 3 of my Patent No. 2,665,- 901, the importance of the modification of the present invention, shown in Fig. 2 of this application will be readily apparent.

The' claims are:

l. In an air "balance, the combination of: a cylinder, one en'd of which is yclosed and the other end of which is open; a pistonf-slidably reciprocable n said cylinder, said piston sufficiently closely tting said cylinder and having suche-substantial length/diameter ratio as to maintain saidpisto'n-and cylinder in co-axial alignment; a dustguard mo'iinted' on said piston and comprising a cylindrical tube concentrically disposed Within said cylinder and extending from'said piston to the open end of said cylinder with the'piston at its maximum extension into said cylinder, the outer surface of said dust guardl being out of contact with and closely spaced from theH inner surface of said cylinder; means for effecting relative reciprocation between said cylinder and said piston; means for supplying lubricating oil to the space between lsaid 'piston and said cylinder, certain portions of said oilV thusrsupplied tending to leak past said piston; oil recovery means disposed adjacent the lower end of saidpiston and above'the upper end of said guard for recovering frm'the walls of said cylinder a major portion of ithe il tending `to leak past said-piston; and means for returning said recovered oil to said lubricating oil supply means.

2. A "combination 'as in claim 1 in which said oil recovery means includes scraper rings mounted on the lower end of said piston which engage said cylinder wall to scrape excess oil therefrom, a reservoir also provided on the lower end of said piston for collecting the oil thus recovered; and pump means for returning said oil from said reservoir to said oil supply means.

3. A combination as in claim 1 in which said oil recovery means includes scraper rings mounted on the lower portion of said piston so as to bear against and scrape oil from said cylinder and deliver said recovered oil inwardly so that the same ilows downwardly within said guard; and a recovered oil reservoir formed in the lower end of said guard, said oil recovery means also including pump means for returning oil thus recovered from said reservoir to said lubricating oil supply means.

4. A combination as in claim 3 in which said means for causing reciprocation between said piston and cylinder includes a piston rod provided on said piston and extending axially therefrom through the open end of said cylinder, said recovered oil reservoir being formed in the lower end of said guard by a bottom wall extending inwardly from said guard and an inner concentric tubular wall extending upwardly from said bottom wall and surrounding said piston rod to center the lower end of said guard on said piston rod.

References Cited in the le of this patent UNITED STATES PATENTS 1,775,733 Phipps Sept. 16, 1930 2,665,774 Patterson Jan. 12, 1954 FOREIGN PATENTS 30,118 Netherlands June 15, 1933 417,445 Germany Aug. 12, 1925 

